1. Field of the Invention
The present invention relates to a pixel and an organic light emitting display device using the same, and more particularly, to a pixel capable of improving response characteristics and displaying an image having a uniform image quality, and an organic light emitting display device using the same.
2. Description of Related Art
Recently, there have been developed various types of flat panel display devices having lighter weight and smaller volume than those of cathode ray tube display devices.
Among these flat panel display devices, an organic light emitting display device displays images by using organic light emitting diodes (OLEDs) which are self-luminescent elements, so that the luminance and color purity of displayed images are excellent. Accordingly, the organic light emitting display device has been in the spotlight as a next-generation display device.
Organic light emitting display devices are categorized into a passive matrix type organic light emitting display device (PMOLED) and an active matrix type organic light emitting display device (AMOLED), depending on a method of driving the organic light emitting diodes.
The AMOLED includes a plurality of pixels positioned at crossing regions of scan and data lines. Each of the pixels includes an organic light emitting diode and a pixel circuit for driving the organic light emitting diode. Here, the pixel circuit generally includes a switching transistor, a driving transistor, and a storage capacitor.
Since the AMOLEDs can operate with low power consumption, they are widely used in portable display devices and the like.
However, response characteristics of a pixel of the AMOLED may be adversely affected by parasitic capacitance generated due to the structure of the pixel, therefore, image quality of an image displayed by a plurality of such pixels may be uneven among the pixels.
For example, in a top-emission type AMOLED in which a pixel includes a pixel circuit and an organic light emitting diode that overlap with each other, a kickback voltage is generated by parasitic capacitance generated between a storage capacitor and an anode electrode of the organic light emitting diode.
The kickback voltage causes a voltage fluctuation at a node coupled to a gate electrode of a driving transistor. Furthermore, the variations of voltage fluctuations occur between frames displaying the same gray level, depending on the gray level of a previous frame. Therefore, response characteristics of a pixel may be worsened, and image quality of an image displayed may be degraded.